In recent years, the number of diabetic patients is increasing with the westernization of eating habits. It is estimated that the number, including potential patients, amounts to 15 million. In the treatment of diabetes, diet therapy and exercise are essential. The objects of these therapies are represented mainly by the maximized normalization of dysbolism of the patients, correction of insulin hyposecretion or insulin resistance which is a factor for causing diabetes, or prevention or inhibition of the advance of vascular complications. Obesity is said to be a prime cause responsible for sixty to eighty percent of diabetes cases. Because excessive insulin secretion is common to most obesity sufferers, there is the possibility that when obesity exceeds a certain level, the secreted amount of insulin becomes too high, leading to deteriorating obesity [Food Style 21, pp. 46, 2002.5 (Vol. 6 No. 5)].
In the U.S.A., with the progress of clinical nutrition science, a variety of oral or tube feeding (enteral) nutritional supplements were developed for various morbidities from the latter half of 1980s to the early 1990s. Examples include “Glucerna” for diabetic patients, “Suplena” for patients with renal disorders who are not receiving artificial dialysis, “Nepro” for patients with renal disorders who require artificial dialysis, “Perative” for all patients during an invasive period, “AlitraQ” for patients during an invasive period, particularly, with impaired digestive tracts, and “Advera” for people with AIDS. In recent years, “OXEPA” for patients with acute respiratory distress syndrome (ARDS) was put on the market. These products account for more than 70% of oral or tube feeding nutritional supplements for morbidities in the U.S.A. [FOOD Style 21, pp 54, 1991.1 (Vol. 3 No. 1)]. In Japan, on the other hand, “YH-80” is a thick fluid diet developed for severe burn patients, “Fibrene YH” having a composition closer to a typical diet than YH80, “Renalene” for patients having diminished renal function, “Meibalance C” which is a total nutrition fluid diet designed for the aged [FOOD Style 21, pp. 58, 1991.1 (Vol. 3 No. 1)], and liquid high-nutrition fluid diet A-3 for unconscious patients [ISO TO RINSHO 29 (17): 4529-4543, 1995] are on the market. Nonetheless, a fluid diet for diabetic patients, such as “Glucerna”, is still not on the market.
A number of patents and patent applications related to fluid diets existent, but the number which relate to diabetes remains few. The only recognized so far is a nutritional composition for diabetic patients which contains protein, lipid and carbohydrate at a predetermined energy percentage and which is added with a viscous soluble food fiber and insulin or hydrolyzate thereof (Japanese Patent Laid-Open No. Hei 11-18725).
An object of the present invention is therefore to provide a nutritional composition effective for nutrition management and blood sugar level control of patients suffering from abnormal glucose metabolism, or for obesity prevention. More specifically, the object of the invention is to provide a nutritional composition for diabetic patients or people having abnormal glucose intolerance, or for prevention of obesity, which composition is effective for suppressing a steep rise in the postprandial blood sugar level due to low insulin secretion and insulin resistance and for improving glycohemoglobin (HbA1c) levels which reflects blood sugar levels over a long period of time.